wiedervergelten
From LSJ
μοῦνοι Ἑλλήνων δὴ μουνομαχήσαντες τῷ Πέρσῃ → alone of all Greeks we met the Persian singlehandedly, alone of all Greeks having fought singlehanded with the Persians
wiedervergelten, par pari referre. – jmdm. w., parem gratiam referre alci (beide im guten und üblen Sinn).